Accepted Manuscript Different therapeutic mechanisms of rigid and semi-rigid mandibular repositioning devices in obstructive sleep apnea syndrome Hokuto Suga , DDS Katsuaki Mishima , DDS, PhD Hiroyuki Nakano , DDS, PhD Asuka Nakano , DDS Mayumi Matsumura , DDS Takamitsu Mano , DDS, PhD Youichi Yamasaki , DDS, PhD Yoshiya Ueyama , DDS, PhD PII:
S1010-5182(14)00163-2
DOI:
10.1016/j.jcms.2014.05.007
Reference:
YJCMS 1814
To appear in:
Journal of Cranio-Maxillo-Facial Surgery
Received Date: 9 February 2014 Revised Date:
8 May 2014
Accepted Date: 8 May 2014
Please cite this article as: Suga H, Mishima K, Nakano H, Nakano A, Matsumura M, Mano T, Yamasaki Y, Ueyama Y, Different therapeutic mechanisms of rigid and semi-rigid mandibular repositioning devices in obstructive sleep apnea syndrome, Journal of Cranio-Maxillo-Facial Surgery (2014), doi: 10.1016/ j.jcms.2014.05.007. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Different therapeutic mechanisms of rigid and semi-rigid mandibular
RI PT
repositioning devices in obstructive sleep apnea syndrome
Hokuto Suga, DDS1; Katsuaki Mishima, DDS, PhD2*; Hiroyuki Nakano, DDS, PhD3;
SC
Asuka Nakano, DDS2; Mayumi Matsumura, DDS2; Takamitsu Mano, DDS, PhD2;
1
M AN U
Youichi Yamasaki, DDS, PhD1; Yoshiya Ueyama, DDS, PhD2
Department of Pediatric Dentistry, Kagoshima University Graduate School of Medical
and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima, Kagoshima 890-8544, Japan Department of Oral and Maxillofacial Surgery, Yamaguchi University Graduate School
TE D
2
of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan Department of Oral and Maxillofacial Surgery II, Kyusyu University Graduate School
EP
3
AC C
of Dentistry, 3-1-1 Maidashi, Higashi, Fukuoka 812-8585, Japan
The work should be attributed to: Department of Oral and Maxillofacial Surgery, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
ACCEPTED MANUSCRIPT
*Corresponding author. Katsuaki Mishima, Department of Oral and Maxillofacial Surgery, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi,
E-mail: [email protected]
SC
Conflict of Interest
RI PT
Ube, Yamaguchi 755-8505, Japan; Phone: +81-836-22-2299; Fax: +81-836-22-2298;
AC C
EP
TE D
M AN U
None declared.
ACCEPTED MANUSCRIPT
INTRODUCTION Obstructive sleep apnea syndrome (OSAS) is the most common sleep-related breathing
RI PT
disorder and a potentially life-threatening condition. Patients with OSAS have increased risk of hypertension, myocardial infarction, cardiac failure, arrhythmia, and cerebral
SC
apoplexy (Hamilton et al., 2004). Therapeutic methods include surgery (Barrera et al.,
M AN U
2007; Gerbino et al., 2014; Schendel and Powell, 2007), continuous positive airway pressure (CPAP), and oral appliance (OA) therapy (Kushida et al., 2006a, 2006b; Aurora et al., 2010).
According to the American Academy of Sleep Medicine (Kushida et al., 2006b),
TE D
OAs are indicated in patients with primary snoring and upper airway resistance syndrome, patients with mild-to-moderate obstructive sleep apnea (OSA) who prefer
EP
OAs to CPAP, and those with severe OSA who refuse CPAP. OAs can be classified into
AC C
mandibular repositioning devices (MRDs) (Ellis et al., 2003) and tongue-retaining devices (TRDs) (Higurashi et al., 2002). These devices are further subdivided on the basis of their design (Ihara et al., 2011), including the type of construction material, configuration, type and location of the coupling mechanism, degree of customization, and amount of vertical opening and lateral jaw movement permitted. As these factors can influence the clinical outcome, they should be considered when applying
ACCEPTED MANUSCRIPT
research-based evidence to clinical practice. MRDs are the most common type of OAs (Chan et al., 2007). Rigid (Blanco et al.,
RI PT
2005; Lam et al., 2007; Hoekema et al., 2008; Petri et al., 2008; Aarab et al., 2011) and semi-rigid (Tan et al., 2002; Nakano et al., 2013) MRDs are mainly used in the clinical
SC
setting. The literature includes several reports of these devices, but their therapeutic
M AN U
mechanisms remain unclear. The purpose of this prospective, nonrandomized clinical study was to clarify the mechanisms of rigid and semi-rigid MRDs in OSAS.
PATIENTS AND METHODS
TE D
Subjects
The study included 20 patients (16 men and four women) with OSAS at Yamaguchi
EP
University Hospital. The patients treated from September 2009 to March 2010 used
AC C
semi-rigid MRDs (n = 13), and those treated from March 2010 to April 2012 used rigid MRDs (n = 7). The two types of devices were not randomly assigned, but based on a date of their first visit. MRDs The rigid MRD consisted of two parts fixing the mandible in a forward position (Fig. 1a). Edge-to-edge occlusion was maintained to avoid side effects such as
ACCEPTED MANUSCRIPT
temporomandibular disorders (TMDs) (Rose et al., 2001; Ferguson et al., 2006; Kushida et al., 2006b; Doff et al., 2012).
RI PT
The semi-rigid MRD comprised upper and lower elements joined by plastic straps from the maxillary canine to the mandibular molar regions. It permitted only forward
SC
movement of the mandible and prevented reduction of the airway during mouth opening.
M AN U
This appliance is generally not associated with side effects such as TMDs (Tan et al., 2002; Nakano et al., 2013), so the mandible was advanced further than the edge-to-edge occlusal position (Fig. 1b). Polysomnographic Examination
TE D
Each patient underwent polysomnography (Alice 5 diagnostic sleep system, Philips Respironics, Best, The Netherlands) at the initial consultation and after symptom
EP
improvement. The apnea-hypopnea index (AHI), apnea index (AI), hypopnea index (HI),
AC C
and lowest oxygen saturation (SpO2) were measured. Apnea was defined as complete cessation of airflow for 10 s and hypopnea was defined as a 50% reduction in oronasal airflow lasting for 10 s with at least 3% desaturation. The AHI was calculated as the number of apnea and hypopnea events per hour of sleep (Kushida et al., 2006b). CT Examination Computed tomography (CT) was also performed twice in each patient: at the initial
ACCEPTED MANUSCRIPT
consultation and after symptom improvement. Multislice helical examinations of the upper airway were performed with holding their breath in supine position, to reproduce
RI PT
the sleep-related breathing condition, in a CT scanner (SOMATOM Definition, Siemens AG, Erlangen, Germany). The slice thickness was 0.6 mm. The scans were
M AN U
Materialise NV, Leuven, Belgium) for analysis.
SC
three-dimensionally reconstructed with image processing software (Mimics version 14.2,
The superior and inferior boundaries of the airway were located at the levels of the hard palate and base of the epiglottis, respectively. The lateral and posterior boundaries were the pharyngeal walls. The anterior boundary was defined by the soft palate, base of
TE D
the tongue, and anterior wall of the pharynx. The following airway morphologic parameters were measured in the reconstructed images: airway volume and
EP
cross-sectional areas and maximum anteroposterior and transverse diameters at the
AC C
levels of the hard palate, tip of the uvula, and tip of the epiglottis (Fig. 2). Statistical Analysis
Data are presented as means ± standard deviations (SD). The Wilcoxon signed-rank test in statistical software (JMP 9.0, SAS, Cary, NC) was used for all comparisons. P < 0.05 was considered significant.
ACCEPTED MANUSCRIPT
RESULTS Initial Assessment
RI PT
The mean age and body mass index (BMI) were 58.1 years and 24.8 kg/m2 in the rigid MRD group and 57.9 years and 23.2 kg/m2 in the semi-rigid MRD group, respectively.
SC
The mean AHI, AI, HI, and lowest SpO2 were 22.0, 7.1, and 10.1 events per hour of
M AN U
sleep and 81.6%, respectively, in the rigid MRD group and 20.5, 7.9, and 12.9 events per hour of sleep and 84.2%, respectively, in the semi-rigid MRD group (Table 1). The groups showed no significant differences in any of these parameters. Symptom Improvement
TE D
The mean AHI significantly improved to 8.9 and 11.5 events per hour of sleep and the mean AI improved to 3.1 and 2.4 events per hour of sleep in the rigid and semi-rigid
EP
MRD groups (P < 0.05), respectively, during the treatment. Only the semi-rigid MRD
AC C
group showed significant improvements (P < 0.05) in the mean HI and lowest SpO2 (Table 2).
The cross-sectional areas measured at the levels of the epiglottic tip and hard palate
significantly increased in the rigid and semi-rigid MRD groups, respectively. No significant differences in the other morphologic measurements were observed (Table 3).
ACCEPTED MANUSCRIPT
DISCUSSION In this study, we investigated the changes in airway form induced by MRDs. Use of the
RI PT
rigid and semi-rigid MRDs significantly increased the cross-sectional areas of the airway at the tongue base and soft palate levels, respectively, implying that these
SC
devices act at different sites. The differences are attributable to structural variations in
M AN U
the MRDs: the rigid MRD moves the mandible forward and fixes its position, thereby repositioning the hyoid bone and tongue anteriorly to maintain airway patency (Liu et al., 2000), whereas the semi-rigid MRD advances the mandible and permits mouth opening to prevent airway obstruction.
TE D
Okushi et al. (2011) endoscopically found that an average mandibular advancement of 13 mm significantly increases the airway space because of palatoglossal and
EP
palatopharyngeal muscle contraction and soft palate enlargement. The significant
AC C
increase in the cross-sectional area at the hard palate level in the semi-rigid MRD group may also be explained by their findings (Ferguson et al., 2006; Kushida et al., 2006b). If the amount of mandibular advancement were increased beyond edge-to-edge occlusion in the rigid MRD group, similar results to those of the Okushi et al. (2011) study might have been obtained. In a previous study, mouth opening reduced the distance between the mandible and
ACCEPTED MANUSCRIPT
the hyoid bone, resulting in backward movement of the hyoid bone and narrowing of the area at the level of the base of the tongue (Lee et al., 2007). However, we did not
RI PT
observe significant narrowing in this region with the semi-rigid MRD. Patients with OSAS using semi-rigid MRDs would not show backward positioning of the tongue
SC
because of the mandibular advancement and opening.
M AN U
Doff et al. (2012) have reported that the risk of developing a temporomandibular disorders (TMDs) appears limited with long term OA use. In the present study, neither the change of the occlusion nor TMDs occurred in the both groups. On the other hand, Tan et al. (2002) have suggested possibility with a few side effects of the semi-rigid
TE D
MRD, but did not reach clear conclusions because of small sample size. As for the indication and contraindication such as TMDs for the OAs, further examination is
EP
necessary.
AC C
OAs have a reported therapeutic efficiency of about 50–80% in mild-to-moderate OSAS (Hoffstein, 2007), and they may be effective even in severe cases (Johal et al., 2005). Approximately 40 kinds of OAs are currently available (Ihara et al., 2011), but they are rarely used on the basis of their site of action. Within the limitations of this study, including the nonrandomized design and small sample size, we conclude that both rigid and semi-rigid MRDs improve respiratory status in patients with OSAS, but
ACCEPTED MANUSCRIPT
they affect different parts of the airway. Therefore, the therapeutic efficiency of MRDs
AC C
EP
TE D
M AN U
SC
RI PT
in OSAS can be improved if they are applied according to their site of action.
ACCEPTED MANUSCRIPT
CONCLUSIONS The mechanisms of rigid and semi-rigid MRDs in OSAS were compared by
RI PT
using polysomnographic and CT examinations. The apnea-hypopnea index significantly improved (P
S1010-5182(14)00163-2
DOI:
10.1016/j.jcms.2014.05.007
Reference:
YJCMS 1814
To appear in:
Journal of Cranio-Maxillo-Facial Surgery
Received Date: 9 February 2014 Revised Date:
8 May 2014
Accepted Date: 8 May 2014
Please cite this article as: Suga H, Mishima K, Nakano H, Nakano A, Matsumura M, Mano T, Yamasaki Y, Ueyama Y, Different therapeutic mechanisms of rigid and semi-rigid mandibular repositioning devices in obstructive sleep apnea syndrome, Journal of Cranio-Maxillo-Facial Surgery (2014), doi: 10.1016/ j.jcms.2014.05.007. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Different therapeutic mechanisms of rigid and semi-rigid mandibular
RI PT
repositioning devices in obstructive sleep apnea syndrome
Hokuto Suga, DDS1; Katsuaki Mishima, DDS, PhD2*; Hiroyuki Nakano, DDS, PhD3;
SC
Asuka Nakano, DDS2; Mayumi Matsumura, DDS2; Takamitsu Mano, DDS, PhD2;
1
M AN U
Youichi Yamasaki, DDS, PhD1; Yoshiya Ueyama, DDS, PhD2
Department of Pediatric Dentistry, Kagoshima University Graduate School of Medical
and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima, Kagoshima 890-8544, Japan Department of Oral and Maxillofacial Surgery, Yamaguchi University Graduate School
TE D
2
of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan Department of Oral and Maxillofacial Surgery II, Kyusyu University Graduate School
EP
3
AC C
of Dentistry, 3-1-1 Maidashi, Higashi, Fukuoka 812-8585, Japan
The work should be attributed to: Department of Oral and Maxillofacial Surgery, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
ACCEPTED MANUSCRIPT
*Corresponding author. Katsuaki Mishima, Department of Oral and Maxillofacial Surgery, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi,
E-mail: [email protected]
SC
Conflict of Interest
RI PT
Ube, Yamaguchi 755-8505, Japan; Phone: +81-836-22-2299; Fax: +81-836-22-2298;
AC C
EP
TE D
M AN U
None declared.
ACCEPTED MANUSCRIPT
INTRODUCTION Obstructive sleep apnea syndrome (OSAS) is the most common sleep-related breathing
RI PT
disorder and a potentially life-threatening condition. Patients with OSAS have increased risk of hypertension, myocardial infarction, cardiac failure, arrhythmia, and cerebral
SC
apoplexy (Hamilton et al., 2004). Therapeutic methods include surgery (Barrera et al.,
M AN U
2007; Gerbino et al., 2014; Schendel and Powell, 2007), continuous positive airway pressure (CPAP), and oral appliance (OA) therapy (Kushida et al., 2006a, 2006b; Aurora et al., 2010).
According to the American Academy of Sleep Medicine (Kushida et al., 2006b),
TE D
OAs are indicated in patients with primary snoring and upper airway resistance syndrome, patients with mild-to-moderate obstructive sleep apnea (OSA) who prefer
EP
OAs to CPAP, and those with severe OSA who refuse CPAP. OAs can be classified into
AC C
mandibular repositioning devices (MRDs) (Ellis et al., 2003) and tongue-retaining devices (TRDs) (Higurashi et al., 2002). These devices are further subdivided on the basis of their design (Ihara et al., 2011), including the type of construction material, configuration, type and location of the coupling mechanism, degree of customization, and amount of vertical opening and lateral jaw movement permitted. As these factors can influence the clinical outcome, they should be considered when applying
ACCEPTED MANUSCRIPT
research-based evidence to clinical practice. MRDs are the most common type of OAs (Chan et al., 2007). Rigid (Blanco et al.,
RI PT
2005; Lam et al., 2007; Hoekema et al., 2008; Petri et al., 2008; Aarab et al., 2011) and semi-rigid (Tan et al., 2002; Nakano et al., 2013) MRDs are mainly used in the clinical
SC
setting. The literature includes several reports of these devices, but their therapeutic
M AN U
mechanisms remain unclear. The purpose of this prospective, nonrandomized clinical study was to clarify the mechanisms of rigid and semi-rigid MRDs in OSAS.
PATIENTS AND METHODS
TE D
Subjects
The study included 20 patients (16 men and four women) with OSAS at Yamaguchi
EP
University Hospital. The patients treated from September 2009 to March 2010 used
AC C
semi-rigid MRDs (n = 13), and those treated from March 2010 to April 2012 used rigid MRDs (n = 7). The two types of devices were not randomly assigned, but based on a date of their first visit. MRDs The rigid MRD consisted of two parts fixing the mandible in a forward position (Fig. 1a). Edge-to-edge occlusion was maintained to avoid side effects such as
ACCEPTED MANUSCRIPT
temporomandibular disorders (TMDs) (Rose et al., 2001; Ferguson et al., 2006; Kushida et al., 2006b; Doff et al., 2012).
RI PT
The semi-rigid MRD comprised upper and lower elements joined by plastic straps from the maxillary canine to the mandibular molar regions. It permitted only forward
SC
movement of the mandible and prevented reduction of the airway during mouth opening.
M AN U
This appliance is generally not associated with side effects such as TMDs (Tan et al., 2002; Nakano et al., 2013), so the mandible was advanced further than the edge-to-edge occlusal position (Fig. 1b). Polysomnographic Examination
TE D
Each patient underwent polysomnography (Alice 5 diagnostic sleep system, Philips Respironics, Best, The Netherlands) at the initial consultation and after symptom
EP
improvement. The apnea-hypopnea index (AHI), apnea index (AI), hypopnea index (HI),
AC C
and lowest oxygen saturation (SpO2) were measured. Apnea was defined as complete cessation of airflow for 10 s and hypopnea was defined as a 50% reduction in oronasal airflow lasting for 10 s with at least 3% desaturation. The AHI was calculated as the number of apnea and hypopnea events per hour of sleep (Kushida et al., 2006b). CT Examination Computed tomography (CT) was also performed twice in each patient: at the initial
ACCEPTED MANUSCRIPT
consultation and after symptom improvement. Multislice helical examinations of the upper airway were performed with holding their breath in supine position, to reproduce
RI PT
the sleep-related breathing condition, in a CT scanner (SOMATOM Definition, Siemens AG, Erlangen, Germany). The slice thickness was 0.6 mm. The scans were
M AN U
Materialise NV, Leuven, Belgium) for analysis.
SC
three-dimensionally reconstructed with image processing software (Mimics version 14.2,
The superior and inferior boundaries of the airway were located at the levels of the hard palate and base of the epiglottis, respectively. The lateral and posterior boundaries were the pharyngeal walls. The anterior boundary was defined by the soft palate, base of
TE D
the tongue, and anterior wall of the pharynx. The following airway morphologic parameters were measured in the reconstructed images: airway volume and
EP
cross-sectional areas and maximum anteroposterior and transverse diameters at the
AC C
levels of the hard palate, tip of the uvula, and tip of the epiglottis (Fig. 2). Statistical Analysis
Data are presented as means ± standard deviations (SD). The Wilcoxon signed-rank test in statistical software (JMP 9.0, SAS, Cary, NC) was used for all comparisons. P < 0.05 was considered significant.
ACCEPTED MANUSCRIPT
RESULTS Initial Assessment
RI PT
The mean age and body mass index (BMI) were 58.1 years and 24.8 kg/m2 in the rigid MRD group and 57.9 years and 23.2 kg/m2 in the semi-rigid MRD group, respectively.
SC
The mean AHI, AI, HI, and lowest SpO2 were 22.0, 7.1, and 10.1 events per hour of
M AN U
sleep and 81.6%, respectively, in the rigid MRD group and 20.5, 7.9, and 12.9 events per hour of sleep and 84.2%, respectively, in the semi-rigid MRD group (Table 1). The groups showed no significant differences in any of these parameters. Symptom Improvement
TE D
The mean AHI significantly improved to 8.9 and 11.5 events per hour of sleep and the mean AI improved to 3.1 and 2.4 events per hour of sleep in the rigid and semi-rigid
EP
MRD groups (P < 0.05), respectively, during the treatment. Only the semi-rigid MRD
AC C
group showed significant improvements (P < 0.05) in the mean HI and lowest SpO2 (Table 2).
The cross-sectional areas measured at the levels of the epiglottic tip and hard palate
significantly increased in the rigid and semi-rigid MRD groups, respectively. No significant differences in the other morphologic measurements were observed (Table 3).
ACCEPTED MANUSCRIPT
DISCUSSION In this study, we investigated the changes in airway form induced by MRDs. Use of the
RI PT
rigid and semi-rigid MRDs significantly increased the cross-sectional areas of the airway at the tongue base and soft palate levels, respectively, implying that these
SC
devices act at different sites. The differences are attributable to structural variations in
M AN U
the MRDs: the rigid MRD moves the mandible forward and fixes its position, thereby repositioning the hyoid bone and tongue anteriorly to maintain airway patency (Liu et al., 2000), whereas the semi-rigid MRD advances the mandible and permits mouth opening to prevent airway obstruction.
TE D
Okushi et al. (2011) endoscopically found that an average mandibular advancement of 13 mm significantly increases the airway space because of palatoglossal and
EP
palatopharyngeal muscle contraction and soft palate enlargement. The significant
AC C
increase in the cross-sectional area at the hard palate level in the semi-rigid MRD group may also be explained by their findings (Ferguson et al., 2006; Kushida et al., 2006b). If the amount of mandibular advancement were increased beyond edge-to-edge occlusion in the rigid MRD group, similar results to those of the Okushi et al. (2011) study might have been obtained. In a previous study, mouth opening reduced the distance between the mandible and
ACCEPTED MANUSCRIPT
the hyoid bone, resulting in backward movement of the hyoid bone and narrowing of the area at the level of the base of the tongue (Lee et al., 2007). However, we did not
RI PT
observe significant narrowing in this region with the semi-rigid MRD. Patients with OSAS using semi-rigid MRDs would not show backward positioning of the tongue
SC
because of the mandibular advancement and opening.
M AN U
Doff et al. (2012) have reported that the risk of developing a temporomandibular disorders (TMDs) appears limited with long term OA use. In the present study, neither the change of the occlusion nor TMDs occurred in the both groups. On the other hand, Tan et al. (2002) have suggested possibility with a few side effects of the semi-rigid
TE D
MRD, but did not reach clear conclusions because of small sample size. As for the indication and contraindication such as TMDs for the OAs, further examination is
EP
necessary.
AC C
OAs have a reported therapeutic efficiency of about 50–80% in mild-to-moderate OSAS (Hoffstein, 2007), and they may be effective even in severe cases (Johal et al., 2005). Approximately 40 kinds of OAs are currently available (Ihara et al., 2011), but they are rarely used on the basis of their site of action. Within the limitations of this study, including the nonrandomized design and small sample size, we conclude that both rigid and semi-rigid MRDs improve respiratory status in patients with OSAS, but
ACCEPTED MANUSCRIPT
they affect different parts of the airway. Therefore, the therapeutic efficiency of MRDs
AC C
EP
TE D
M AN U
SC
RI PT
in OSAS can be improved if they are applied according to their site of action.
ACCEPTED MANUSCRIPT
CONCLUSIONS The mechanisms of rigid and semi-rigid MRDs in OSAS were compared by
RI PT
using polysomnographic and CT examinations. The apnea-hypopnea index significantly improved (P
